Photographic copying apparatus

ABSTRACT

A photographic copying apparatus wherein the light source is an elongated electronic flash lamp and the reflector is a hollow pyramid which surrounds the lamp and diverges in a direction toward the support for copying material. The symmetry axis of the reflector coincides with the axis of the lamp. A polygonal light mixing duct is installed between the support for copying material and the open base of the reflector, and that end of the duct which is remote from the reflector contains a pane of light diffusing material. The walls of the reflector are cold light mirrors which transmit heat. One or more guides for color filters are installed between the base of the reflector and the adjacent end of the mixing duct. Such end of the mixing duct registers at least with the major part of the base.

[111 3,734,614 51 May 22,1973

[S4] PHOTOGRAPHIC COPYING APPARATUS [75] Inventor: Wolfgang Zahn,Munich, Germany [73] Assignee: Agfa-Gevaert Aktiengesellschatt,

Leverkusen, Germany 22 Filed: June7, 1971 21 Appl.No.: 150,435

[30] Foreign Application Priority Data Brendel ..355/67 X Clark..240/106 X Primary Examiner-Samuel S. Matthews AssistantExaminer-Michael L. Gellner Attorney-Michael S. Striker [57] ABSTRACT Aphotographic copying apparatus wherein the light source is an elongatedelectronic flash lamp and the reflector is a hollow pyramid whichsurrounds the lamp and diverges in a direction toward the support forcopying material. The symmetry axis of the reflector coincides with theaxis of the lamp. A polygonal light mixing duct is installed between thesupport for copying material and the open base of the reflector, andthat end of the duct which is remote from the reflector contains a paneof light diffusing material. The walls of the reflector are cold lightmirrors which transmit heat. One or more guides for color filters areinstalled between the base of the reflector and the adjacent end of themixing duct. Such end of the mixing duct registers at least with themajor part of the base.

8 Claims, 2 Drawing Figures PATENTEUHAYZZ I973 INVENTOR WOLFGANG ZAHN0x40! $"Lr 1 PHOTOGRAPHIC COPYING APPARATUS BACKGROUND OF THE INVENTIONThe present invention relates to photographic copying apparatus ingeneral, and more particularly to improvements in those components ofphotographic copying apparatus which are used to generate and directlight against copying material.

It is already known to employ in a photographic copying apparatus a lamphouse which contains an incandescent-lamp with a thread-like filamentlocated in the symmetry axis of the reflector. The reflector is a hollowcone which presents serious problems, especially as concerns thewithdrawal of heat. Thus, a conical reflector cannot be assembled ofcold light mirrors. Furthermore, since the filament is located in thesymmetry axis of the hollow conical reflector, all of the energy whichis radiated from the lamp and is reflected on any portion of theinternal surface of the conical reflector is caused to pass through theregion of the filament and toward the portion which is locateddiametrically opposite the light reflecting portion. This brings aboutextremely high concentration of energy in the region of the filament sothat the latter is destroyed after relatively short periods of use.

It was also attempted to employ in photographic copying apparatus lightsources in the form of electronic flash lamps. Such lamps are desirablewhen it is necessary to produce high concentrations of light. Animportant advantage of electronic flash lamps is that their light outputis very high and thattheir heat radiation is relatively low. Theattemptsto use electronic flash lamps failed mainly because thedimensions of such lamps are rather large-so that they were notconsidered satisfactory for illumination of relatively small prints.

SUMMARY OF THE INVENTION An object of the invention is to provide aphotographic copying apparatus with novel and improved means forgenerating, mixing and confining copying light.

Another object of the invention is to provide a photographic printingapparatus with a lighting arrangement whose light output is high, whosedimensions are relatively small, and which can insure uniformillumination of copying material.

A further object of the invention is to provide a lighting arrangementwhich is constructed and assembled in such a way that it canautomatically dissipate substantial amounts of heat.

An additional object of the invention is to provide a photographiccopying apparatus with a novel light source and with a novel reflectorfor the light source.

The invention is embodied in a photographic copying apparatus whichcomprises a support for photosensitive copying material, an elongatedrod-like electronic flash lamp which constitutes the light source andhas a first end nearer to and a second end remote from the support forcopying material, and a reflector surrounding the-lamp and diverging inadirection from the second toward the first end of the lamp. The symmetryaxis of the reflector (which is preferably a hollow three-, fourormore-sided pyramid) preferably coincides with the longitudinal axis ofthe lamp. The height of the reflector preferably equals or approximatesthe length of the lamp, and the reflector preferably consists of partlytransmitting mirrors, especially cold light mirrors which transmitsubstantial amounts of heat.

A hollow preferably polygonal light mixing duct can be installed betweenthe open base of the reflector and the support for copying material.That end of the duct which is adjacent to the support preferablycontains a plate of light-diffusing material and its other end is placedinto substantial or full registry with the open base of the reflector.One or more guides for color filters may be provided between the ductand the open base of the reflector.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved copying apparatus itself, however, both as to its constructionand its mode of operation, together with additional features andadvantages thereof, will be best understood upon perusal of thefollowing detailed description of certain specific embodiments withreference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary schematicsectional view of the light generating, mixing and confining componentsof a photographic copying apparatus which embodies the invention; and

FIG. 2 is an end elevational view of the light source and reflector asseen in the direction of arrows from the line 11- of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1,there is shown a portion of a photographic copying apparatus whichcomprises a hollow pyramidal reflector 1 having four triangular walls 1aeach of which consists of partly heat transmitting material. Inaccordance with a preferred embodiment of the invention, the walls laconstitute cold light mirrors which can transmit substantial amounts ofheat. The light is generated by an elongated rod-like source 2 which isan electronic flash lamp having a longitudinal axis which coincides withthe symmetry axis of the reflector 1 (see FIG. 2). The terminals of thelamp 2 are indicated but not specifically referenced in FIG. 1. Theenergy source for the lamp 2 is shown at 102. It will be noted that theheight of the pyramidal reflector 1 slightly exceeds the length of thelamp 2; however, it is equally possible to make the reflector 1 shorterso that its height actually equals or approximates the length of thelamp 2.

The area of the open upper end portion (as viewed in FIG. 1) or base lbof the reflector 1 preferably equals or approximates the area of thephotosensitive printing or copying material 3 which is to be exposed tolight furnished by the lamp 2. The printing material 3 is adjacent to asupport here shown as a negative mask 4.

The exact manner in which the mask 4 or another suitable support ismounted in or on the housing of the photographic copying apparatus formsno part of the present invention. It suffices to say that one end of thelamp 2 is nearer to and that the other end of the lamp is more distantfrom the mask 4, and that the reflector l diverges in a direction fromthe other toward the one end of the lamp 2.

In accordance with an additional feature of the invention, the copyingapparatus further comprises a polygonal light mixing duct 5 which isdisposed between the base 1b of the reflector 1 and the mask 4. Theinternal surface of the duct 5 reflect light and the light which issuesfrom the upper end of the duct 5 (as viewed in FIG. 1) must pass througha light diffusing plate 6 of opal glass or the like. The purpose of theduct 5 is to insure intensive mixing of light which enters its openlower end and to thus guarantee that the material 3 is exposed tohomogeneous printing light. The axial length or height of the duct 5preferably exceeds its maximum transverse dimension; most preferably,the axial length of the duct 5 is at least twice its maximum transversedimension. The cross-sectional area of the duct 5 preferablyapproximates or equals the area of the material 3, i.e., the area ofthat part of the material 3 which is to be exposed to printing orcopying light. In accordance with still another feature of theinvention, the copying apparatus comprises one or more guides 107 forone or more color filters 7 which can be introduced into the spacebetween the base lb of the reflector 1 and the adjacent lower open endof the mixing duct 5. The filter or filters 7 may constitute subtractivecolor filters which are moved across the path of light issuing from thebase 1b to terminate the exposure of printing material to light in therespective color or colors, or they may constitute a means for coloringthe light which issues from the base lb and is to impinge upon theprinting material. If the illustrated filters are a substractive colorfilters, they serve as a means for blocking the transmission of light ofa particular color to thus terminate the exposure of printing materialto such light. If the illustrated filters 7 are light coloring filters,they may be introduced across the path of light which passes into themixing duct 5 in such a way that they intercept some or all of the lightwhich issues from the base lb of the reflector 1. The non-uniformcoloration of light which passes through a coloring filter and entersthe duct 5 disappears not later than when the light passes through theopal glass plate 6.

The operation of the copying apparatus will be readily understooduponperusal of the preceding description. As shown in FIGS. 1 and 2, thelight beams which issue from any selected point of the lamp 2 are eitherreflected on the internal surfaces of the reflector l or enter directlyinto the mixing duct 5. For example, the point 2a of the lamp 2 emitslight beams each of which is caused to enter the lower end of the mixingduct 5, either directly or upon reflection on the internal surfaces ofthe walls 1a. This holds true for the light beam 2b which enters theduct 5 without reflection, for the light beam 20 which is reflected onlyonce prior to entry into the duct 5 and for the light beam 2d which isreflected several times prior to entry into the duct.

The majority of light beams which enter the lower end of the duct 5 areinclined with reference to the axis of the lamp 2 so that such lightbeams are reflected again on the internal surfaces of the duct. Thus,the opening angle of beams which leave the reflector l by way of theopen base lb is normally less than 180. Therefore, the improvedapparatus exerts at least some directional effect upon the light whichenters the mixing duct. The latter insures further homogenization oflight which is homogenized again during passage through the opal glassplate 6 to insure soft and uniform illumination of printing material.

It was found that the space requirements of the just describedilluminating arrangement are surprisingly low.

The reflector 1 may be assembled of three, four or more cold lightmirrors to form a three-, fouror moresided hollow pyramid, and its openbase is preferably in at least substantial but most preferably in fullregistry with the open lower end of the mixing duct 5.

An important advantage of the improved copying apparatus is that theheat emission of electronic flash lamp 2 is relatively low. Therefore,the apparatus is not overheated even if the pyramidal reflector l isreplaced with a conical reflector diverging in a direction from that endof the lamp which is remote from the support for printing materialtoward the support. However, a pyramidal reflector is preferred at thistime because the light which is reflected on its internal surface doesnot have to pass across the lamp 2 but can be reflected around the lamp(see FIG. 2) prior to reaching the open base 1b to enter the adjacentopen end of the mixing duct 5.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featureswhich fairly constitute essential characteristics of the generic andspecific aspects of my contribution to the art and, therefore, suchadaptations should and are intended to be comprehended within themeaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

I claim:

1. In a photographic copying apparatus, a combination comprising asupport for copying material; an elongated rod-like electronic flashlamp having a first end nearer to and a second end remote from saidsupport; a hollow pyramidal reflector surrounding said lamp anddiverging in a direction from said second toward said first end, saidreflector having an axis of symmetry coinciding with the axis of saidlamp; and a light mixing duct interposed between said reflector and saidsupport to mix at least some of the light which issues from said lampand at least some of the light which is reflected by said reflectorbefore such light reaches the copying material.

2. A combination as defined in claim 1, wherein the height of saidpyramid at least approximates the length of said lamp.

3. A combination as defined in claim 1, wherein said reflector consistsof at least three partly heat transmitting mirrors.

4. A combination as defined in claim 3, wherein said mirrors are coldlight mirrors.

5. A combination as defined in claim 1, wherein said duct has a firstopen end facing said support and a second open end facing saidreflector, said reflector having an open end adjacent to the second openend of said duct and further comprising light dispersing means extendingacross the first open end of said duct.

6. A combination as defined in claim 1, wherein said duct is providedwith light-reflecting internal surfaces and has an end adjacent to saidsupport, the crosssectional area of said end of said duct at leastapproximating the area of copying material at said support.

7. A combination as defined in claim 1, wherein said reflector has anopen end in the region of said first end of said lamp and said duct hasan open end adjacent to and said duct and at least one filter movablewith referand at least substantially registering with the open end ofsaid reflector.

8. A combination as defined in claim 1, further comprising guide meansdisposed between said reflector 5 ence to said guide means across thepath of at least some light which enters said duct.

1. In a photographic copying apparatus, a combination comprising a support for copying material; an elongated rod-like electronic flash lamp having a first end nearer to and a second end remote from said support; a hollow pyramidal reflector surrounding said lamp and diverging in a direction from said second toward said first end, said reflector having an axis of symmetry coinciding with the axis of said lamp; and a light mixing duct interposed between said reflector and said support to mix at least some of the light which issues from said lamp and at least some of the light which is reflected by said reflector before such light reaches the copying material.
 2. A combination as defined in claim 1, wherein the height of said pyramid at least approximates the length of said lamp.
 3. A combination as defined in claim 1, wherein said reflector consists of at least three partly heat transmitting mirrors.
 4. A combination as defined in claim 3, wherein said mirrors are cold light mirrors.
 5. A combination as defined in claim 1, wherein said duct has a first open end facing said support and a second open end facing said reflector, said reflector having an open end adjacent to the second open end of said duct and further comprising light dispersing means extending across the first open end of said duct.
 6. A combination as defined in claim 1, wherein said duct is provided with light-reflecting internal surfaces and has an end adjacent to said support, the cross-sectional area of said end of said duct at least approximating the area of copying material at said support.
 7. A combination as defined in claim 1, wherein said reflector has an open end in the region of said first end of said lamp and said duct has an open end adjacent to and at least substantially registering with the open end of said reflector.
 8. A combination as defined in claim 1, further comprising guide means disposed between said reflector and said duct and at least one filter movable with reference to said guide means across the path of at least some light which enters said duct. 